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Do you really have to slash and burn to upgrade your storage?

Software defining the future

“Contrail will look at the servers they have and install a virtual router in each one. Then all it cares about is when OpenStack creates a new VM, and when it does it will provide connectivity with the other virtual routers.

“It's a layer of virtualisation, not using VLANs and not dependent on the hardware. It starts and ends in two servers. You can run an entire data centre over one VLAN, all at layer three and using any switches because we don't interact with the hardware. It creates a sort of private virtual network, and then creates VPN tunnels within that.”

Virtualising the tomayto

Of course, SDN – like storage virtualisation – means different things to different people, and the industry has come up with at least three different ways to implement it, depending on how much you want to involve the hardware. At one extreme, Cisco is building programmability into its big switches, while at the other virtualisation specialists have developed overlays where a virtual SDN sits in a VLAN on the network and in virtual routers on the server hypervisors. In between are the more hybrid approaches such as OpenDaylight, using OpenFlow to control and direct packet flows on the physical network.

Khurram Khawaja, Alcatel-Lucent's enterprise core and data centre product management director suggests it might be better to back off and take a broader look. . "SDN is more of a methodology, an architecture and approach for solving the problems that enterprises typically cannot solve," he argues. He offers the example of virtual machine mobility in the data centre – you can create a VM very quickly now, but if the network can't adapt there is still a lot of manual reconfiguration required.

"One of our North American healthcare customers was maintaining a really long script to do VM mobility, which was a really tedious process and meant it could take weeks to move a VM, rather than minutes," he continues. "Now with SDN they can do it in a few clicks.".

He adds: "The way we see SDN is quite a bit different from network automation – SDN is the promised land where the network responds to application automation and provides feedback on what is and isn't possible."

On that basis, an SDN is indeed the network equivalent of server and storage virtualisation. It gives you a set of network objects, such as virtualised switches, routers and firewalls that can be deployed in a highly automated manner. In this, it resembles network function virtualisation (NFV), which is the process of running more and more network services from firewalls and intrusion prevention systems to load balancers and WAN optimisers as virtual appliances rather than physical ones.

However, whether it is servers, storage or networks, simply moving from physical to virtual achieves little beyond the initial reduction in power and rack-space consumption if you still have to manage it manually. It is only once you add some dynamic intelligence to a virtualised technology, linking that automated deployment to the needs of the business that you can start to see wider benefits.

In addition, networking is infrastructure and it is inherently harder to develop and deploy innovative infrastructure compared, for example, to innovative consumer applications or even enterprise storage, says Neela Jacques, executive director at the OpenDaylight project, which is developing an open-source SDN framework. He contrasts the way that consumer app start-ups can be based in San Francisco, Berlin or London, and run by younger people with relatively little history in technology, whereas an infrastructure start-up still needs deep subject knowledge and will probably need to be based somewhere more technical.

"There's tons of storage start-ups – the reason is you need knowledge of the technology and the background, but as long as you can find something you can do better than everyone else and you can persuade some IT managers to let you in, you can grow from there," he says. "You haven't seen that level of start-ups in networking because you don't have the same dynamic. We've tended to have one big vendor and some second places. It is inherently harder in networking to find a corner of the data centre and say 'My innovation goes here'. The network is fundamentally connected and interoperable, and the cost and risk of choosing the wrong technology in networking is far higher than in other areas.

“Having a green field lowers the risk. You can start from scratch, standardise on certain technologies. There are ways for SDN to come into brown field sites though – for example, traffic shaping is one way you can add some level of programmability." He adds that one advantage of the open source approach is that it is pretty cheap to evaluate and implement – it just needs a VM to run the OpenDaylight software.

So, if IT agility is important to you, or if you are having difficulty keeping up with change requests, SDN and storage virtualisation could be the answer. Whatever the size of your organisation, if the network is big and busy enough to need network and storage administrators, it is probably big and busy enough to benefit from virtualisation.

You still have to know your infrastructure and ask the important questions though, warns Tony Lock. “You have to know what you've got in your organisation,” he concludes. “Do you know where it all is, what's on it, and what are your business rules on looking after it? Then it's what can we do, what risks are we willing to accept? You have to know where you are in order to work out how to use it more effectively.” ®

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